FIG. 4.

The C1-INH-mediated inhibition of the classical complement cascade is potentiated by TagA from A. hydrophila SSU. Increasing amounts of C1-INH (2, 8, and 16 μg) were treated with 1 μg of rTagA (or heated rTagA), treated with 1 μg of the metalloprotease elastase from P. aeruginosa, or left untreated overnight at room temperature. On the next day, opsonized sheep erythrocytes were mixed with the C1-INH overnight-incubated reaction mixture, as described in Materials and Methods. After incubation for 1 h at 37°C, the erythrocytes were pelleted and the OD₄₁₂ of the supernatant was measured. * denotes statistically significant values (P ≤ 0.05).